Momsen recounted the incident during an interview (embedded at the top of this post) with SiriusXM host Jose Mangin at the 2014 Rock on the Range fest, revealing that Gibbons announced his arrival on stage by grabbing her backside. "He was just lookin' for some tush," she laughed to Mangin. "It's fine. Worse things could happen."

When Mangin shared that he wouldn't have minded being in the same situation, Momsen continued, "I just didn't see him walk on stage. I thought it was [Blackhearts guitarist] Acey [Slade]. I was like, 'What the f--- just happened?' I turned my head...and Billy's right here."

With the Pretty Reckless' new record 'Going to Hell' breaking into the Top Five of Billboard's album charts, perhaps Momsen can use that encounter to call on Gibbons for a guest appearance on a future project. "It was great, good times," she insisted. "He's Billy Gibbons, a legend. The first time I met him, I bowed down to him."